108,000 Bees
Is there no limit to the size a bee colony can grow? It is generally thought that a bee colony's population will max out at about 63,000. This calculation is based on worker bees living for six weeks and their queen laying 2000 eggs a day during the peak of spring, and 500 bees a day dying through natural attrition.
But, factoring in weather events, like weeks of rain, can drastically reduce the time foragers spend outside the nest. Limited flight time reduces natural attrition, and a colony's population can balloon to more than 100,000 - like this monster we recently removed from a house in Booroobin near Maleny.
For this massive increase in numbers to occur, the nest must be very well provisioned with copious amounts of stored honey and pollen (bee bread) so that the colony can continue to be well fed through the many days of confinement. For this reason, it will only be the massive nests that swell in numbers. The newer, less established nests that don't have the resources to continue raising new baby bees will actually start to decrease in numbers drastically during prolonged periods of being unable to forage.
One of the amazing traits of the super-organism that is a bee colony, is their collective ability to work within their means. This is especially evident during a pollen dearth. The pollen is the protein source required by young nurse bees to excrete the royal jelly fed to developing larvae. With no incoming protein, the queen will reduce the number of eggs she lays, or the worker bees will start to eat those eggs to preserve enough protein for the brood that they can raise.
When making these observations of wild or feral bee nests, the take-home message for beekeepers is to always leave plenty of honey on your colonies for the rainy days. Besides, honey is much easier to store on your hives rather than in buckets.
PS. How do we know there were 108,000 bees. No, we didn't count every bee. We weighed our bee-vacuum at the end of this job and found more than 31 pounds (14kg) of bees in the box. 3,500 bees weigh about 1 pound (450g).